Combination machine for cutting plaster casts



June 23, 1936. J. w. OBANION COMBINATION MACHINE FOR CUTTING PLASTER CASTS Filed Oct. 17, 1934 INVENTOR. JOHN W. 0'5

A T TORNE Y Patented June 23, 1936 UNITED STATES COMB INATION MACHINE FOR CUTTING PLASTER CASTS John w. OBanion. Yuba City, Calif. Application October 1'1, 1934, Serial No. 748,648

5 Claims.

The present invention relates to improvements in a combination machine for cutting plaster casts and its principal object is to provide a machine of the character described that will allow a plaster cast to be cut expeditiously and without inconvenience to the patient.

More particularly it is proposed in the present invention to provide a motor driven cutting machine, in which two different cutter heads or tools are provided and are connected, through proper trains of gearing to the motor in such a manner that either of the cutter heads may be used at the option of the operator.

It is further proposed in the present invention to provide one cutter head that has a shearing effect and may be used for cutting the plaster cast from one end thereof while another cutter head employs a rotary saw and may be used for cutting a window in an intermediate portion of the plaster cast for observation purposes.

It is further proposed in thepresent inventionto arrange the former cutter head in such a manner that a guide forming one of the elements of the shearing device rides on top of the plaster.

cast while the second element of the shearing device is introduced underneath the cast and works toward the guide and away from the body of the patient whereby discomfort to the latter may be minimized during the shearing action.

It is further proposed to provide, in addition to the two cutter heads, a drill adapted for attachment to the same motor for drilling holes into the plaster cast preliminary to the use of the cutter heads to provide a starting point for cutting a window into the plaster cast by means of the shearing device.

It is further proposed to provide, in combination with the drill attachment an adjustable means for limiting the depth of cut of the drill to correspond to the thickness of the plaster cast.

Further objects and advantages of my invention will appear as the specification proceeds.

The preferred form of myinvention is illustrated in the accompanying drawing in which- Figure lis a side elevation of my machine, a portion being shown in longitudinal section,

Figure 2 a transverse section through the machine taken along line 2-2 of Figure 1,

Figure 3 a detail section taken along line 33 of Figure 2, and- Figure 4 a detail view, in longitudinal section ofa drill attachment-to the device.

While I have shown only the preferred form of my invention I wish to have it understood that various changes or modifications may be made within the scope of the claims hereto attached without departing from the spirit ofthe invention.

In its preferred form my invention comprises a motor I having a handle 2 projecting axially meshes with a third gear a short distance as shown at 5 and a second short shaft 6 extends into the housing in parallel relation to the first shaft. These two shafts are interconnected through the pinion I and the gear 8. A second gear 9 is mounted on the shaft 6 and Ill on the shaft II which extends clear through the housing to and through the opposite wall I 2. The end of this shaft is squared as at l3 and extends into a cylindrical projection I3 and is adapted for connection to a registering socket i4 provided in the sleeve housing of a rotary cutting tool I5 described in my Patent No. 1,942,766 granted on January 8, 1934. It will be noted, particularly from an inspection of Figure 2, that the shaft II with its squared end I3 is offset relative to the center line of the second cutting tool to be described hereafter which makes it'adapted for direct connection to the rotary cutting tool without interfering with the operation of the second cutting tool.

The latter tool which is indicated at I 6, comprises two shanks l'l of rectangular cross section arranged in spaced and parallel relation and having their ends mounted in a socket are held by two screws l9, and a third shank 20 interposed between the two shanks with freedom of rectilinear movement, the third shank being guided by means of a pin 20' secured in the outer shanks and extending through a slot 2| in the third shank. The socket l8 has a reduced cylindrical extension 22 revolvably fitting in a registering recess 23 in the housing 3, where it may be secured against rotation by a set screw 24. The upper end of the central shank 20 is formed with a vertical slot 25 terminating in an undercut recess 26 adapted to receive the neck 21 and the head 28 of a short shaft 29 bearing on the upper edge of the central shank, the outer shanks l1 being suitably slotted as at 3'l to accommodate those portions of the head 28 projecting beyond the thickness-of the central shank.

The shaft 29 is connected, through a link 3| pinned to the forked end thereof as shown at 32, with an eccentric 33 revolvably mounted in the housing 3 on a stub shaft 34 and formed integrally with a large gear 35 which meshes with a pinion 36 formed integrally with the gear l0 so that reciprocating movement is imparted to the central shank through the pinion 1, gear 8, pinion 9, gear Ill, pinion 36, gear 35, eccentric 33 and the link 3|. It willbe noted that the two shanks H, which are stationary may be turned about their center line by adjustmentof' the their underfaces, are intended to ride on the plaster cast while the shearing element 38, which forms part of the central shank and reciprocates therewith, is made in the form of a tapered shoe and adapted to be inserted underneath the plaster.

A second handle 4| extends laterally from the housing 3 for facilitating the manipulation of the device.

The operation of my device may be readily understood from the foregoing description. To use the reciprocating cutter the operator grabs the device by means of the two handles 4 and 4i, adjusts the shearing elements by turning the socket 18 so that they project in the desired direction, then places the shoe 38 beneath the .cast until the edge of the cast is disposed between the two shearing elements. The operator then presses on the switch and exerts slight forward pressure. The motor causes the lower shoe to be moved toward the'upper shearing elements and a narrow strip of the plaster is shorn off and forced by the lower element through the space between the upper elements.

The rotary cutter may be attached to the gearing when desired and its operation does not in any way interfere with the operation of the reciprocating shears.

For cutting a window into the plaster cast I may use either the rotary cutter l5 shown in Figure l or a drill attachment illustrated in Figure 4 which may be substituted for the rotary cutter and which may be connected in the same manner to the square end ii of the shaft II. The attachment comprises a casting 42 consisting of a collar 43 having a sleeve 44 projecting from one end and a second sleeve 45 from the opposite end. The sleeve 44 fits in the cylindrical projection l3 and may be secured therein by means of the set screw 48. The sleeve 45 is threaded externally. The casting has a partition wall 41 between the sleeves and in this partition wall is-supported a drill bit 48 having a socket 49 within the-sleeve 44, the. socket being adapted for engagement with the squared end l3 of the shaft H. The drill bit is held against endwise motion by the socket 49 and a collar 50 bearing onopposite faces of the partition 41.

The drill bit projects beyond the free end of the threaded sleeve 45 and in order to adjustably limit the depth of penetration of the drill bit I provide the cap 5| which consists of a cylindrical body 52 having an internal flange 53 at one end adapted to be threaded on the sleeve 45 and a second internal flange 54 at the other end which encircles the projecting drill bit, allowing only a small portion of the same to become active. The active length of the drill bit may be readily adjusted by adjusting the cap on the sleeve 45 and the cap may be locked in position by a lock nut If the operator wishes to use the attachment for cutting a window in a plaster cast he first determines the thickness of the plaster, than sets the cap 52 so that the active length of the drill bit corresponds to the thickness of the plaster and drills an outline into the outline of the window. He may then use this hole as a starting point for using special shears corresponding to those shown in Figures 1 and 2 but of smaller dimensions so that they may be introduced through the hole drilled into the plaster.

I claim:

1. In a machine for cutting plaster casts, a driving head comprising a housing, a drive shaft extending thereinto, a driven shaft mounted parallel to the drive shaft, gearing between the shafts, an eccentric geared to the driven shaft, a reciprocating cutter driven by the eccentric, the driven shaft being 'ofiset relative to the eccentric drive and having an extension passing and clearing the eccentric drive and adapted for connection to a rotary element.

2. In a machine for cutting plaster casts, a driving head comprising a housing, a drive shaft extending thereinto through one wall thereof, a driven shaft mounted parallel to the drive shaft, reduction gearing interposed between the two shafts, a journal projecting into the housing from the opposite wall in spaced relation to the driven shaft, an eccentric on said journal, a driving connection between the driven shaft and the eccentric, an element reciprocable transversely to the direction of the shafts and a driving connection between the eccentric and the reciprocable element.

3. In a machine for cutting plaster casts, a driving head comprising a housing, a drive shaft extending thereinto through one wall thereof, a driven shaft mounted parallel to the drive shaft, reduction gearing interposed between the two shafts, a journal projecting into the housing from the opposite wall, an eccentric on said journal, a driving connection between the driven shaft 4 and the eccentric, an element reciprocable transversely to the direction of the shafts and a driving connection between the eccentric and the reciprocable element, the driven shaft being arranged in offset relation to the driving connection for the reciprocable element and extending past the same to the opposite wall of the housing and adapted for driving a rotary element independently of the eccentric drive.

4. In a machine for cutting plaster casts, a pair 50 of shanks arranged in spaced relation, a third shank intermediate the pair and reciprocable longitudinally thereof, cutting elements on the shanks adapted to cut through an interposed plaster cast, a housing, a socket mounted in housing with freedom of rotary adjustment and having the pair of shanks secured therein, a reciprocating element in the housing having a head extending between the shanks of the pair for engagement with the third shank, the latter being secured to the reciprocating element with freedom of rotary motion about the axis of the socket.

5. In a machine of the character described, a cutter head comprising a pair of straight shanks arranged in spaced relation, 9. third straight shank of similar shape movable between the two,

means for rectilinearly and longitudinally guiding the third shank, means for reciprocating the third shank, and cutting elements projecting rectangularly from the pair of shanks andthe third shank and being adapted to coact in cutting an interposed object.

JOHN W. OBANION.

the 55 

